| Co-Investigator(Kenkyū-buntansha) |
TABATA Masaaki Saga University, Faculty of Science and Engineering, Associate Professor, 理工学部, 助教授 (40039285)
OZUTSUMI Kazuhiko University of Tsukuba, Department of Chemistry, Assistant Professor, 化学系, 講師 (50177250)
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| Research Abstract |
The effect of complexing agents (polyphosphates, aminopolycarboxylates, etc.) on the redox reactions of vanadium (V) or copper (II) wiht iron (II) has been studied by means of potentiometry. The redox reaction of copper (II) with iron (II) favorably proceeds by the presence of diphosphate and 2, 9-dimethyl-1, 10-phenanthlorine (neocuproine) to form the copper (I) -neocuproine complex. This reaction has been applied to the photometric determination of iron (II) with a flow injection analysis.
Structure of copper (II) complexes with pyridine, 2, 2'-bipyridine, 1, 10-phenanthlorine, and aminocarboxylates in aqueous solution has been determined by the EXAFS method. The mono-, bis-, tris-, and tetrakis (pyridine) copper (II) complexes have an axially elongated octahedral structure. The structure othe mono- and tris-complexes of 2, 2'-bipyridine and 1, 10-phenanthlorine is also distorted octahedral. In these complexes the equatorial Cu-O and Cu-N bond distances are slightly lengthened with in
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creasing the average ligand numbers. The axial Cu-O and Cu-N distances are practically the same except for the tetrakis (pyridine) copper (II) complex, in which the Cu-O bond distance is appreciably lengthened probably due to the steric repulsion. The bis (2, 2'-bipyridine) copper (II) complex has a five-coordinate trigonal bipyramidal structure. The Cu-O bond distance within the complex is much longer than that within the hexaaquacopper (II) ion and the mono-complexes. The mono- and bis (aminocarboxylato) copper (II) complexes have an axially elongated octahedral structure. Both equatorial and axial Cu-N and Cu-O bond distances virtually remain unchanged upon the formation of the mono-and bis-complexes independent of aminocarboxylate ions employed.
Kinetics and mechanism of the ligand-substitution reaction of zine (II), cadmium (II), and lead (II) -porphyrins with ethylenediaminetetraacetic acid (EDTA) has been studied. The reaction mechanism on the replacement of zinc (II) porphyrin with EDTA is largely different from that of cadmium (II) or lead (II) -porphyrins. The large differences in the reactivities of zinc (II), cadmium (II), and lead (II) porphyrins have been applied to the determination of trace zinc (II) in the presence of a large amount of cadmium (II) or lead (II). It is also shown that, in the molecular complex formation oo porphyrins with nucleotides, the hydrophobic interaction between porphyrin and nucleotides is more important than the electrostatic interaction. Less
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